1. Field of the Invention
This disclosure relates to an organic light emitting display device and a driving method thereof.
2. Related Art
An organic electro-luminescence (EL) element (or an organic light emitting diode (OLED)) employed in an organic light emitting display device is a self-emissive display in which a light emitting layer is formed between two electrodes. In the organic EL element, electrons and holes are injected into a light emitting layer from an electron injection electrode (or a cathode) and a hole injection electrode (or an anode), respectively, and excitons formed as injected electrons and holes are combined to emit light when shifted from an excited state to a ground state.
In the organic light emitting display device, when scan signals, data signals, power, and the like, are supplied to subpixels disposed in a matrix form, selected subpixels emit lightto display an image.
Some organic light emitting display devices have a subpixel structure including red, green, blue, and white colors (referred to as ‘RGBW OLED’, hereinafter). The RGBW OLED is driven such that subpixels selected from among RGB subpixels are further turned on in a display panel in order to correct white color coordinates.
The RGBW OLED lowers luminance through a peak luminance control (PLC) method in a particular image (consuming much power) in order to maintain power consumption below a target level. The PLC method is a method of implementing maximum luminance by varying a gamma voltage according to an average picture level (APL) calculated for a maximum component of an RGB data signal.
In a PLC method, a contrast ratio (CR) is enhanced by increasing luminance of a particular image in order to enhance perceptual picture quality, rather than lowering power consumption. However, the use of the PLC method may exceed a consumption power limit level of the RGBW OLED despite decrease in power consumption. Therefore, the PLC method should be improved to operate the RGBW OLED within the consumption power limit.